In cable transmission systems, it is common practice to connect the power serially to the repeater amplifiers and to loop the power back at an intermediate position in the system. With this arrangement, it is necessary to provide a switch so that either the through power or loop power option may be selected at the repeater site. Of necessity, such a switch must be rugged, low cost, substantially foolproof and yet readily altered to select the option preferably without removal of any protective cover or other part.